Structural and electrical characterizations of n-type implanted layers and ohmic contacts on 3C-SiC

Song, Xiaoshi; Biscarrat, J.; Michaud, Jean-François; Cayrel, Frédéric; Zieliński, Marcin; Chassagne, Thierry; Portail, Marc; Collard, Emmanuel; Alquier, Daniel

doi:10.1016/j.nimb.2011.06.004

Cited by 14 publications

(13 citation statements)

References 29 publications

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“…After the PIA process, Second Ion Mass Spectrometry (SIMS) analysis was conducted on samples from each dose batch for the toughest PIA condition (1375°C, 2 hours) as shown in Fig 2. The profiles before PIA were not shown here but were expected to be much like the annealed ones due to the unlikely observable diffusion of nitrogen in 3C-SiC below 1800°C [17,24]. High dose and medium dose samples both achieved an implantation depth of ~300nm with peak values around 6x10 20 …”

Section: Sims Profilesmentioning

confidence: 84%

“…A series of energies with increasing total doses were applied during implantation to form box profile at 3 doping levels, which will be called high dose, medium dose and low dose samples in following text. Nitrogen was selected as the dopant rather than phosphorous since it does less damage to the 3C-SiC film [17,18], although it saturates more readily [8]. Prior to the PIA process, 1μm thick SiO 2 was deposited on the surface of half samples from each batch via plasma enhanced chemical vapour deposition (PECVD).…”

Section: Methodsmentioning

confidence: 99%

“…For 3C-SiC on Si wafers, the PIA temperature is limited by the melting point of Si (1412°C), well below that of SiO 2 (1610°C) [9] so a SiO 2 capping layer can be a good choice. Previously, n-type heavily implanted 3C-SiC was studied for different annealing conditions with [17] and without [18,19] a graphite cap. A study of using deposited SiO 2 as the PIA capping layer for 3C-SiC on Si is demonstrated here.…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Sharma

Shah

et al. 2015

Applied Surface Science

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A degenerated wide bandgap semiconductor is a rare system. In general, implant levels lie deeper in the bandgap and carrier freeze-out usually takes place at room temperature. Nevertheless, we have observed that heavily doped n-type degenerated 3C-SiC films are achieved by nitrogen implantation level of ~6x10 20 cm -3 at 20K. According to temperature dependent Hall measurements, nitrogen activation rates decrease with the doping level from almost 100% (1.5x10 19 cm -3 , donor level 15meV) to ~12% for 6x10 20 cm -3 . Free donors are found to saturate in 3C-SiC at ~7x1019 cm -3 . The implanted film electrical performances are characterized as a function of the dopant doses and post implantation annealing (PIA) conditions by fabricating Van der Pauw structures. A deposited SiO 2 layer was used as the surface capping layer during the PIA process to study its effect on the resultant film properties. From the device design point of view, the lowest sheet resistivity (~1.4mΩ.cm) has been observed for medium doped (4x10 19 cm -3) sample with PIA 1375°C 2h without a SiO 2 cap.Keywords: 3C-SiC; post-implantation activation; Van der Pauw; Hall; degenerated film IntroductionSilicon carbide (SiC) has been considered as the future power devices materials attributed to its superior electrical, mechanical and thermal properties. 3C-SiC has a smaller bandgap (2.3eV) than 4H-SiC (3.2eV), but still 2 times higher than Si (1.1eV) and can be grown directly on large area Experimental ProceduresThe materials studied in this work was a 10μm thick unintentionally doped (<1x10 16 cm -3 ) 3C-SiC film epitaxial grown on a 4 inch Si(100) substrate by NOVASiC. The wafer went through a chemical-mechanical polishing process [20] after the CVD growth with an initial surface RMS roughness ~0.2nm determined from atomic force microscopy (AFM) measurements. A Veeco multimode AFM with Nanonis controller was used to evaluate the surface roughness. The overall roughness value was determined by scanning three 10x10μm 2 areasand averaging the results. The wafer was cut into 30 8x8mm 2 pieces and equally divided into 3 batches. An onaxis nitrogen implantation process was conducted on the plain surface of all samples at room temperature. A series of energies with increasing total doses were applied during implantation to form box profile at 3 doping levels, which will be called high dose, medium dose and low dose samples in following text. Nitrogen was selected as the dopant rather than phosphorous since it does less damage to the 3C-SiC film [17,18] SIMS profilesAfter the PIA process, Second Ion Mass Spectrometry (SIMS) analysis was conducted on samples from each dose batch for the toughest PIA condition (1375°C, 2 hours) as shown in Fig 2. The profiles before PIA were not shown here but were expected to be much like the annealed ones due to the unlikely observable diffusion of nitrogen in 3C-SiC below 1800°C [17,24]. High dose and medium dose samples both achieved an implantation depth of ~300nm with peak values around 6x10 20 cm -3 and 4x10 1...

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Section: Sims Profilesmentioning

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Sharma

Shah

et al. 2015

Applied Surface Science

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“…It was also studied and resulted a similar surface roughness level as a graphite cap with the same annealing conditions [21]. In the few literatures on 3C-SiC, n-type implanted 3C-SiC was studied for different annealing conditions (1150-1400°C) with [22] and without [23,24] a graphite cap, and it turned out that there was little advantage of using a graphite cap in terms of protecting the 3C-SiC surface, probably because the temperature limited by Si substrates is not high enough to make the difference. For a given implanted doping level, the active dopant concentration in SiC generally increases with the PIA temperature.…”

Section: Thermal Diffusion and Ion Implantationmentioning

confidence: 99%

Main Differences in Processing Si and SiC Devices

Li¹,

Jennings²

2018

Disruptive Wide Bandgap Semiconductors, Related Technologies, and Their Applications

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Due to the different physical properties of Si and SiC, many conventional Si device processing techniques cannot be directly transferred to SiC device fabrication. To deliver high-performance SiC commercial power devices, new techniques quite different from Si industry were developed in past decades for processing device, such as dopant implantation, metal contact, MOS interface, etc. On the other hand, the physics model behind many of these SiC processing technologies is not updated in the same pace that the success of them can still not be fully understood.The activation of dopants in 4H-SiC has been intensively studied, and the efforts are mainly put into two directions, namely, protecting the semiconductor surface morphology while at the same time maximising the active concentration of implanted dopants. Figure 1. Schematic graph showing a typical dopant thermal diffusion process using a gas source. Main Differences in Processing Si and SiC Devices

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Crystal recovery from Al‐implantation induced damaging in 3C‐SiC films

Severino¹,

Piluso²,

Marino

et al. 2012

Physica Rapid Research Ltrs

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3C-SiC is considered an attractive material for power electronics devices due to its excellent properties such as higher theoretical electron mobility (~900 cm 2 V -1 s -1 ) and lower interface state density between SiC and SiO 2 when compared to the most technological mature 4H-SiC polytype. Both these properties make 3C-SiC very attractive for metal-oxide -semiconductor field effect transistors (MOSFETs) working in medium-and high-power regimes [1]. Moreover, single crystal 3C-SiC is grown at a lower temperature than 4H-SiC and heteroepitaxy with large-area Si substrates is allowed, thus reducing drastically the cost for its production [2]. The epitaxy of doped 3C-SiC films is easily achievable by using gaseous dopants during the growth process with nitrogen and aluminium as most used doping species [3,4]. A much harder step is the definition of localized doping region underneath the drain and/or source for MOSFET realization. The most used technique to obtain such structures is to implant N, Al or B ions in the desired regions [5,6]. For p-type doping, Al is preferred due to its shallow energetic levels and, consequently, lower activation energy (0.24 eV). Ion implantation processing, on the other hand, involves the scattering of the ordered atoms in SiC lattice with high-energetic ions (from tenth to thousands keV) resulting in a damaging of the crystal structure of the hosting material.In this study, a 10 μm thick 3C-SiC film has been processed to realize an Al + -implanted layer underneath the film surface. The structural damaging and recovery due to the implantation processing and subsequent thermal annealing have been evaluated by means of X-ray diffraction (XRD) and micro-Raman spectroscopy (μ-Raman). Reciprocal space mapping (RSM) of the (004) 3C-SiC reciprocal lattice point (RLP) was then used to further study the recovery at different temperatures.3C-SiC was grown in a chemical vapor deposition (CVD) reactor by using a multi-step growth process [7]. 3C-SiC growth process was performed on a (001)-oriented Si substrate by using ethylene (C 2 H 4 ), trichlorosilane Damaging in Al-implanted 3C-SiC and subsequent crystal recovery due to thermal treatments up to 1350 °C are evaluated by X-ray diffraction and micro-Raman spectroscopy. Reciprocal space mapping of (004) 3C-SiC planes shows a lowintensity implantation-induced secondary peak at higher interplanar spacing in the as-implanted 3C-SiC sample, with a generated misfit between the implanted and the epitaxial region of about 0.6%. Increasing the annealing temperature from 950 °C to 1350 °C, the secondary peak is gradually reabsorbed within the epitaxial 3C-SiC reciprocal lattice point. Finally, the disappearance of the secondary peak after a 1350 °C thermal treatment is observed. Thus, implantationinduced average strain, resulting in a severe 3C-SiC deforma-tion, has been totally relieved at the highest annealing temperature.

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Structural and electrical characterizations of n-type implanted layers and ohmic contacts on 3C-SiC

Cited by 14 publications

References 29 publications

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Electrical activation of nitrogen heavily implanted 3C-SiC(1 0 0)

Main Differences in Processing Si and SiC Devices

Crystal recovery from Al‐implantation induced damaging in 3C‐SiC films

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